In many applications, the safe coupling of connectors is of high importance. For example, in the case of car safety systems, as for example airbag systems in passenger cars, the connectors used for the connection of an airbag to its ignition base have to be provided with reliable safety mechanisms. To ensure that the connectors cannot become loose unintentionally, secondary locking members are known to guarantee a safe mechanical coupling.
A typical example of an airbag squib connector provided with a secondary locking member is known from EP 1 207 591 B1. In this publication, an airbag plug connector is described comprising a plug connector housing with a plug in portion, which is adapted to be plugged into the corresponding receptacle of an airbag igniter or airbag squib. The plug part of the connector comprises a pair of locking arms, which are adapted to latch into a corresponding latching groove provided in the counter connector. To secure this latch type connection, the connector does further comprise a secondary locking member, also often denoted as connector position assurance device (CPA). This secondary lock is arranged moveable on the plug connector housing in mating direction of the plug connector between an open and a locked or closed position. In the open position, the secondary locking member projects to some extent from the upper surface of the plug connector and in this open position it is possible to mate the plug connector with the corresponding counter connector. After the mating process is complete, the secondary lock can be moved manually into the locked or closed position. In this locked position, locking legs provided on the secondary locking member prevent a release movement of the locking arms of the plug connector. From this prior art document it is also known to provide the secondary locking member with a mechanism, that prevents that the secondary member can be put into the locked position, if no counter connector is present, i.e. when the plug connector is not mated. This mechanism utilizes a spring arm with a step, which rests on a protrusion of the plug connector housing and prevents that the secondary lock can be brought into the locked position. Upon mating with the counter connector, this spring arm is deflected by a portion of the counter connector, so that upon full mating it is possible to move the secondary lock into the locked position, thereby securing the mated condition of the two connectors.
To facilitate the assembly of such plug connectors having secondary locking systems, spring actuated secondary locking mechanisms were developed. EP 1 540 778 B1 describes for example a plug-in connector comprising a secondary locking mechanism impinged by a spring force. In this publication a plug-in connector for airbag restraint systems is suggested, which comprises a secondary locking mechanism and four compression or pressure springs. The pressure springs are arranged, such that upon mating of the plug connector with the corresponding counter connector, the secondary lock is moved by the counter connector from the locked position to the open position against the pressure forces of the springs. At the end of the mating process, the secondary lock is suddenly released, and the four springs press the secondary lock back into the closed or locked position, thereby securing the mating process automatically.
The construction of this connector works very well, however, the skilled person is always trying to find improvements. It would be in particular desirable, to achieve a spring operated secondary locking mechanism, which is more compact in design and which is easier to assemble. The choice of pressure springs as in the prior art requires suitable guiding structures in the connector housing, since the compressed spring requires a spring buckling prevention. Further, since the pressure springs are loosely arranged in the corresponding guide structure, a risk exists, that these loose parts get lost during assembly and it is difficult to integrate the mounting of the springs in a fully automated assembly process.